Multi-well plates, also known as microtiter plates or microwell plates, are standard products in clinical and research laboratories. A multi-well plate is a flat plate with multiple wells used as individual test tubes. The most common multi-well plates include 96-wells or 384-wells arranged in a rectangular matrix. ANSI has set standardized dimensions and SBS footprints for well-plates. For example, a 96-well plate has 8 rows and 12 columns of wells centered 9 millimeters centerline-to-centerline. A typical 384-well plate includes 16 rows and 24 columns of wells with a centerline-to-centerline distance of 4.5 millimeters. Multi-well plates with 1536 wells and higher are also available. Some multi-well plates are designed to hold larger volumes than a standard multi-channel plate yet maintain the standard centerline-to-centerline dimensions. These well-plates are taller and are commonly called deep well-plates.
In the laboratory, multi-well plates are filled with various liquid samples, and it is routine to transfer liquid samples from one multi-well plate to another in order to implement assays or store duplicate samples. It is also routine to transfer liquid reagents or samples from a common reservoir to either a standard multi-well plate or a deep well-plate. In some cases, hand-held, multi-channel pipettes, for example 8 or 12 channels, are used to draw some or all the liquid from a set of wells in a wellplate and transfer aliquots into another set of wells on the same wellplate or another wellplate. In order to produce a high volume of prepared multi-well plates, automated liquid handling machines have been developed to provide much higher throughput than a technician, even with a multi-channel pipettor. In the art, there are several types of automated liquid handling machines to automatically fill multi-well plates. Such automated liquid handling machines typically use sophisticated Cartesian robots for positioning syringes and/or pipette tips, as well as shuttling well-plates from storage and into position for liquid transfer. Most of these automated liquid handling machines are rather expensive, and also quite large. Many include sophisticated computer control which requires extensive training, as well as setup and programming.
Such automated high-throughput systems are not practical for some applications. In order to address this need, the prior art also includes a simultaneous 96-well manual pipetting system sold under the trade name Liquidator 96. This fully manual system includes an array of pipette tip fittings matching the dimensions of a standard 96-well plate. Disposable pipette tips are mounted to the 96-fittings. The system aspirates and dispenses liquid from the 96-pipette tips simultaneously. Because the system is fully manual, it lacks the ability to program precise protocols and liquid transfer amounts. For example, an electronic hand-held pipettor, or an automated liquid handling system, can be programmed to aspirate a precise volume of liquid reagent or sample and then dispense the aspirated volume, sometimes as a series of equal-volume aliquots in successive dispensing operations. Programmable electronic hand-held pipettors as well as automated liquid handling systems can also be configured to do quite complex pipetting operations, such as mixing, repeat pipetting, diluting, etc.
While programmable, automated liquid handling systems have many desirable features over a fully manual 96-well liquid transfer system, they are generally too large and expensive for use in certain laboratory applications. Therefore, in many applications, laboratory technicians are resigned to using multi-channel hand-held pipettors, which may be quite time-consuming.